"""
Here is my coding space
    Caffeineholic
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"""
N, H = map(int, input().split())

time = [0 for _ in range(H+1)]

for i in range(N):
    a, b = map(int, input().split())
    time[a] += 1
    time[b+1] -= 1
for i in range(H-1):
    time[i+1] = time[i]+time[i+1]
print(max(time[:-1]))